The immunopathogenesis of Multiple Sclerosis will be examined using anti-idiotypic antibodies prepared to CSF-immunoglobulin G. The heterologous anti-idiotype will be used to characterize both "private" and "public" (disease-associated/disease-related) idiotypes among the oligoclonal CSF immunoglobulin G using a double antibody precipitation radioimmunoassay (RIA). Cross-idiotypy among MS patients will be examined by competitive RIA. Brain antigens and common viruses will be tested as competitors in an effort to identify the antibody specificities of the CSF immunoglobulin. Finally the anti-idiotypic antisera will be used in the examination of immunoregulatory cells present in the blood and CSF of both normal individuals and MS patients.